The existing forming device has the drawback illustrated in accompanying FIG. 1 in that the space for receiving the formed sheet, i.e. the insert, is not constant in the direction of the corrugation. Actually, since profiles A and B are identical, the separation in the y direction is obviously constant for all the values of x in a system of x, y coordinates, but the thickness in the inclined areas, such as, for example, at point E is less than that at the top areas S of the profiles. As a result, the existing forming devices do not allow one to obtain the best shape at every point of the heat exchange surfaces and, moreover, cause tears where the space for receiving them is the narrowest.
The present invention aims at proposing a forming device of the type mentioned above and a method for producing the forming plates, which alleviate the above-mentioned drawbacks.